Two-photon imaging of cancer cell extravasation in live mice

Abstract MDA-MB-231 breast cancer cells were engineered to express cytoplasmic paxillin-GFP and nuclear H2B-mCherry. In order to image extravasation, the cancer cells were injected in the blood stream of nude mice. Using 2-photon excitation microscopy we can simultaneously excite the two probes and also visualize the autofluorescence of tissues. A skin flap was opened to visualize blood vessels and recognize the position of the cancer cells. Two-photon imaging showed that after an initial phase in which the cells are non-adherent, some cells spread on the internal surface of the capillaries. Days later some cells started to appear on the external side of the capillary. The extravasated cells extend very long protrusions into the tissue. The goal was to determine if at the end of the long protrusion, if it is possible to observe the formation of focal adhesions by imaging paxillin-GFP. Preliminary results show that when cells start to adhere to the blood vessel wall they form focal adhesions as determined by the characteristic elongated features observed in the paxillin-GFP channel. New approaches will allow the tracking of the tip of the protrusion to determine if focal adhesions are forming there as the cells extravasate. This is important in establishing the mechanism of cell extravasation and migration in tissues. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1412. doi:10.1158/1538-7445.AM2011-141

CARPE-ID: Continuously Adaptable Re-identification for Personalized Robot Assistance

In today's Human-Robot Interaction (HRI) scenarios, a prevailing tendency exists to assume that the robot shall cooperate with the closest individual or that the scene involves merely a singular human actor. However, in realistic scenarios, such as shop floor operations, such an assumption may not hold and personalized target recognition by the robot in crowded environments is required. To fulfil this requirement, in this work, we propose a person re-identification module based on continual visual adaptation techniques that ensure the robot's seamless cooperation with the appropriate individual even subject to varying visual appearances or partial or complete occlusions. We test the framework singularly using recorded videos in a laboratory environment and an HRI scenario, i.e., a person-following task by a mobile robot. The targets are asked to change their appearance during tracking and to disappear from the camera field of view to test the challenging cases of occlusion and outfit variations. We compare our framework with one of the state-of-the-art Multi-Object Tracking (MOT) methods and the results show that the CARPE-ID can accurately track each selected target throughout the experiments in all the cases (except two limit cases). At the same time, the s-o-t-a MOT has a mean of 4 tracking errors for each video

Real-time imaging of 3-dimensional cancer cell movement in tissues

Abstract Our knowledge of how cells move in 3D in tissues is limited due to the lack of imaging methods that can produce 3D images fast enough and with sufficient resolution. Cancer cells migrate in 3D by forming adhesion points at the end of very long cellular protrusions. These protrusions are very thin and it is difficult to visualize adhesions along the protrusion surface. Conventional 3D stack reconstruction has relatively low resolution unless it is done using many frames. This results in a very slow acquisition in 3D confocal microscopy. Faster methods of 3D data acquisition (spinning disk microscopy) cannot be easily implemented since there is significant amount of scatter in tissues. A major obstacle in imaging adhesions is to find and track them so that they will not go out of focus. We are developing a new method which is based on orbiting imaging around cellular protrusions to visualize protein dynamics during extravasation. A feedback mechanism controls the center of the orbit to be at the center of the fluorescence distribution. A program reconstructs the shape of the protrusions in 3D. The fluorescence intensity in one or more channels is also simultaneously measured. The fluorescence intensity of one channel is used to paint the protrusion shape, which results in the 3D reconstruction of the protrusion. During the orbit, the second channel of the microscope measures the second harmonic generation (SHG) signal. We then correlated the appearance of bright fluorescence spots on the protrusion surface with the points of contact of the protrusion. This method will enable imaging of cancer cell invasion in 3-dimentions in live mice in real time. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4750. doi:10.1158/1538-7445.AM2011-475

Raster-image-correlation spectroscopy of paxillin-GFP-expressing breast cancer cell in vitro and in vivo

Abstract Raster-image-correlation spectroscopy (RICS) is a noninvasive technique to detect and quantify events in the living cell, including concentrations of molecules and their diffusion coefficients. Any cell containing a fluorophore that can be imaged with a laser scanning microscope can be analyzed with RICS. We obtained RICS images with an Olympus FluoView FV1000 confocal microscope using Olympus FluoView software to acquire data and SimFCS software to perform RICS analysis. Paxillin is involved in the assembly of focal adhesions, which was linked to green fluorescent protein (GFP) for the current study. In this study, we describe RICS of paxillin-GFP expression in breast cancer cells (MDA-MB-231) in vitro and in vivo. Slow-moving membrane-bound paxillin proteins were measured in live breast cancer cells in vitro. Paxillin-GFP-expressing breast cancer cells (1×106) were injected in the epigastric cranials vein of the nude mouse. Paxillin-GFP-expressing breast cancer cells became attached to the inner vessel wall within 3 hours after injection. Rapidly-moving cytosolic paxillin-GFP molecules were imaged with RICS. With the ability to measure the molecular dynamics of paxillin in cancer cells in vitro and in vivo by RICS, we are now capable of studying the role of both slow-moving paxillin in the cell membrane and rapidly-moving cytosolic paxillin in cancer-cell behavior. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5183. doi:1538-7445.AM2012-518

TESSX: A Mission for Space Exploration with Tethers

Tethers offer significant potential for substantially increasing payload mass fraction, increasing spacecraft lifetime, enhancing long-term space travel, and enabling the understanding and development of gravity-dependent technologies required for Moon and Mars exploration. The development of the Tether Electrodynamic Spin-up and Survivability Experiment (TESSX) will support applications relevant to NASA's new exploration initiative, including: artificial gravity generation, formation flying, electrodynamic propulsion, momentum exchange, and multi-amp current collection and emission. Under the broad term TESSX, we are currently evaluating several different tether system configurations and operational modes. The initial results of this work are presented, including hardware development, orbital dynamics simulations, and electrodynamics design and analysis

Multi-contact planning and control for humanoid robots: Design and validation of a complete framework

In this paper, we consider the problem of generating appropriate motions for a torque- controlled humanoid robot that is assigned a multi-contact loco-manipulation task, i.e., a task that requires the robot to move within the environment by repeatedly establishing and breaking multiple, non-coplanar contacts. To this end, we present a complete multi-contact planning and control framework for multi-limbed robotic systems, such as humanoids. The planning layer works offline and consists of two sequential modules: first, a stance planner computes a sequence of feasible contact combinations; then, a whole-body planner finds the sequence of collision-free humanoid motions that realize them while respecting the physical limitations of the robot. For the challenging problem posed by the first stage, we propose a novel randomized approach that does not require the specification of pre-designed potential contacts or any kind of pre-computation. The control layer produces online torque commands that enable the humanoid to execute the planned motions while guaranteeing closed-loop balance. It relies on two modules, i.e., the stance switching and reactive balancing module; their combined action allows it to withstand possible execution inaccuracies, external disturbances, and modeling uncertainties. Numerical and experimental results obtained on COMAN+, a torque-controlled humanoid robot designed at Istituto Italiano di Tecnologia, validate our framework for loco-manipulation tasks of different complexity

Omnidirectional Walking Pattern Generator Combining Virtual Constraints and Preview Control for Humanoid Robots

This paper presents a novel omnidirectional walking pattern generator for bipedal locomotion combining two structurally different approaches based on the virtual constraints and the preview control theories to generate a flexible gait that can be modified on-line. The proposed strategy synchronizes the displacement of the robot along the two planes of walking: the zero moment point based preview control is responsible for the lateral component of the gait, while the sagittal motion is generated by a more dynamical approach based on virtual constraints. The resulting algorithm is characterized by a low computational complexity and high flexibility, requisite for a successful deployment to humanoid robots operating in real world scenarios. This solution is motivated by observations in biomechanics showing how during a nominal gait the dynamic motion of the human walk is mainly generated along the sagittal plane. We describe the implementation of the algorithm and we detail the strategy chosen to enable omnidirectionality and on-line gait tuning. Finally, we validate our strategy through simulation experiments using the COMAN + platform, an adult size humanoid robot developed at Istituto Italiano di Tecnologia. Finally, the hybrid walking pattern generator is implemented on real hardware, demonstrating promising results: the WPG trajectories results in open-loop stable walking in the absence of external disturbances

The Fitting length of finite soluble groups II: Fixed-point-free automorphisms

Let G be a finite soluble group, and let be the Fitting length of G. If φ is a fixed-point-free automorphism of G, that is , we denote by the composition length of . A long-standing conjecture is that , and it is known that this bound is always true if the order of G is coprime to the order of φ. In this paper we find some bounds to in function of without assuming that . In particular we prove the validity of the “universal” bound . This improves the exponential bound known earlier from a special case of a theorem of Dade

Corrigendum: The Walk-Man Robot Software Architecture

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